JPH08160839A - Color image forming device - Google Patents

Abstract

PURPOSE: To provide a color image forming device, wherein it is easy to perform small high-speed maintenance. CONSTITUTION: Image forming units 1, 2 and 3 are the same and taking the image forming unit 1 as an example, a scanner unit 31 is attached to a frame 30, a photosensitive drum 33, a roller charger 35 and a developer 34 integrally formed for a process cartridge are freely attached/detached to/from the frame 30, the scanner unit 31 and the process cartridge for each frame 30 are integrally loaded/unloaded to/from a device main body, the image forming units are longitudinally arrayed, carrier belts 9, 10, 11, 12 and 13 and transfer roller 14, 15, 16 and 17 are placed in upper and lower directions, feeding means 5, 6, 23, 24 and 8 are placed in the lower direction and a fixer 18 is placed in the upper direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam printer (hereinafter referred to as LBP) and a color image forming apparatus used in a copying machine. Among them, the present invention relates to a color image forming apparatus that is high-speed, small-sized, easy to maintain, low in cost, and does not select the type of transfer material.

[0002]

2. Description of the Related Art Conventionally, a color image forming apparatus is a relatively low speed apparatus in which four color developing devices are arranged around a photosensitive drum having a large diameter, and a latent image is formed for each color and then developed. , A multiple transfer method in which four colors are sequentially transferred onto a transfer material wound around a transfer drum, or a four-color developing device is arranged around the photosensitive drum, and a toner image formed on the photosensitive drum is temporarily intermediate-transferred. An intermediate transfer member transfer method is known in which transfer is performed on a body and then collectively transferred from an intermediate transfer member to a transfer material.

In the multiple transfer system, a transfer material is wound around a transfer drum and the toner is transferred for each color, so that the image is excellent and the registration of the images of the respective colors is relatively easy. The intermediate transfer member transfer method is characterized in that the toner of four colors is once transferred to the intermediate transfer member and then further transferred to the transfer material, so that the type of transfer material is not so selected.

Further, as a high speed color image forming apparatus,
There is known a four-drum system in which image forming units are arranged in a horizontal direction for four colors and toner is sequentially transferred each time the photosensitive drum is passed. The 4-drum system forms an image with four colors at a time, and is therefore very suitable for speeding up.

[0005]

However, the above-mentioned conventional example has the following problems.

The multiple transfer system is suitable for speeding up because it requires the selection of the type of transfer material in order to transfer it by winding the transfer material around the transfer drum, and the process of developing sequentially. Absent.

In the intermediate transfer member transfer method, latent images are sequentially formed and four color toner images are sequentially transferred to the intermediate transfer member.
Finally, the color image on the intermediate transfer member is collectively transferred to the transfer material. Therefore, since the transfer is performed twice, deterioration of the image is likely to occur, and for the process of sequential development, Not suitable for speeding up.

The four-drum system is apt to be large in size because four image forming sections are provided, and therefore the cost is high.
There is a disadvantage that registering is relatively difficult.

Further, in any of the conventional configurations as described above, each image forming section constitutes a part of the configuration of the main body, and its handling requires a specialized technique, and the maintenance by the user is required. It wasn't designed to work.

An object of the present invention is to provide an image forming apparatus which is small in size and easy to handle and maintain.

[0011]

According to the present invention, four small image forming units, which are the same except for toner, are arranged in the vertical direction, and the main part of the image formation is made into a cartridge, which is transferred to a transfer material or an intermediate transfer member. By doing so, a high-speed color image forming apparatus which is small in size, low in cost, and excellent in image and which does not select a transfer material is provided.

The present invention has the following configuration.

According to a first aspect of the present invention, an image exposing means, an image carrier, a charging means, a developing means each having a toner of a different color, or a cleaning means in addition to these or a cleaning means in addition thereto. A plurality of image forming units each having a transfer unit are vertically arranged, and a transport path and a transport unit for vertically transporting the transfer material through the plurality of image forming units, a sheet feeding unit for feeding the transfer material to the transport path, A color image forming apparatus having fixing means for fixing a transfer material after transfer, wherein the image forming unit integrally includes at least one of a charging means, a developing means, a cleaning means, and a transfer means and an image carrier. A color image forming apparatus comprising the above process cartridge and an image exposing unit.

According to a second aspect of the present invention, the apparatus main body includes an image exposure unit, an image carrier, a charging unit, a developing unit having toners of different colors, or an image forming unit having a cleaning unit in addition thereto. A plurality of vertically removably arranged intermediate transfer members are arranged between the respective image carriers and the transfer means of the plurality of image forming units, and the intermediate transfer member is arranged on the downstream side in the moving direction of the intermediate transfer member. 1. A color image forming apparatus, comprising: a sheet feeding means for feeding a transfer material, a transfer means, and a fixing means for fixing the transfer material after transfer, wherein the image forming unit includes a charging means, a developing means, and a cleaning means. A color image forming apparatus comprising an image forming unit including a process cartridge in which at least one of them and an image carrier are integrated, and an image exposing unit.

A third aspect of the present invention is characterized in that the image forming units each have an image exposing means and a process cartridge in a frame body, and each frame body can be attached to and detached from the apparatus main body. The color image forming apparatus according to the first invention.

A fourth aspect of the present invention is characterized in that the image forming units each have an image exposing means and a process cartridge in a frame body, and each frame body is detachable from the apparatus main body. 2 is a color image forming apparatus according to the invention.

A fifth aspect of the present invention is the color image formation according to the first or third aspect, characterized in that the distance between the image bearing members is smaller than the length of the minimum size transfer material. It is a device.

A sixth invention of the present invention is any one of the first to fifth inventions, characterized in that the image carrier constituting the image forming unit is a small diameter drum having an outer diameter of 40 mm or less. And the color image forming apparatus.

A seventh invention of the present invention is the color image forming apparatus as described in any one of the first to sixth inventions, wherein the image exposing means is a laser exposing means.

An eighth aspect of the present invention is characterized in that the process cartridge is integrally formed as a cartridge and is attachable to and detachable from the frame of the image forming unit.
Alternatively, it is the color image forming apparatus according to the second invention.

A ninth aspect of the present invention is characterized in that the image forming unit is attachable to and detachable from the apparatus main body.
Alternatively, it is the color image forming apparatus according to the second invention.

A tenth aspect of the present invention is the color image forming apparatus according to the eighth or ninth aspect, wherein the process cartridge is detachably mountable to an image forming unit attached to an apparatus main body. It is a device.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows a schematic configuration of an embodiment of a color image forming apparatus according to the present invention.

In the figure, the image forming units 1, 2, 3, 4 are
Scanner units 31, 3 each having an optical unit and a scanning unit for irradiating and scanning the photosensitive drums 33, 38, 43, 48 with laser light emitted in accordance with image information.
7, 42, 47 and photosensitive drums 33, 38, 43, 48 provided as image carriers, photosensitive drums 33, 38, 4
Charging rollers 35, 4 provided as charging means for 3, 48
0, 45, 50, developing devices 34, 3 provided as developing means
9, 44, 49, cleaning means 36, 41, 46,
51 is a unit type image forming means including a main image forming means such as 51, and toners of yellow (Y), magenta (M), cyan (C), and black (Bk) are respectively supplied to the developing devices 34, 39, 44. , 49.

FIG. 2 shows a schematic structure of an image forming unit of the color image forming apparatus used in FIG. The image forming units 1, 2, 3 and 4 have the same configuration except for the toner, and therefore the image forming unit 4 containing yellow toner will be described.

The main structure of the image forming unit is a frame body 30.
The scanner unit 47 and the process cartridge 60 are provided on the upper side. A laser system is suitable as the exposure means of this image forming unit. This is because a small-diameter photosensitive drum is suitable for making the apparatus small and stabilizing the separation of the transfer material, and a laser system that requires a small width of the exposure means is used for making the photosensitive drum of a small diameter. Most suitable. Other LED systems take a width on the photosensitive drum,
It is unsuitable for the construction of a small-diameter photosensitive drum.

Scanner units 31, 37, 42, 4
No. 7 has the same configuration, and even if the color of the toner is different, all are the same except for the toner.

Further, this image forming unit can be slid and drawn out to the front side orthogonal to the paper surface of FIG.
Easy to replace.

The scanner unit 47 is arranged on the frame 30, and the laser light is emitted from the opening 32 and is incident on the photosensitive drum 48.

The process cartridge 60 comprises a photosensitive drum 48, a charging roller 50, a developing device 49 and a cleaning means (not shown) which are integrally formed, and can be easily removed and attached. The process cartridge 60 includes the drum shaft 4 of the photosensitive drum 48.
The frame body 30 is fitted with the frame body 8a so that the positional relationship between the process cartridge 60 and the scanner unit 47 can be accurately obtained. The process cartridge 60 has the same configuration for all four colors and is exactly the same except that the toner is different. A gear (not shown) is fixed to the drum shaft 48a, and when the image forming unit 4 is mounted on the apparatus main body, it meshes with a drive gear (not shown) provided on the apparatus main body side. Rotational force can be transmitted through this drive gear. Alternatively, the clutch may be fixed to the drum shaft 48a, and the drive clutch provided on the apparatus main body side may be engaged with the image forming unit 4 when the image forming unit 4 is mounted on the apparatus main body.

When the main part of the image formation is made of the common member as described above, the lot of parts is increased and the kinds of parts are decreased, so that the usefulness is improved and the cost is reduced.

FIG. 3 shows a schematic structure of a process cartridge used in the image forming unit of the color image forming apparatus used in FIG. As described above, the process cartridge 60 has the same configuration except for the toner. Therefore, the image forming unit 4 containing the yellow toner described in FIG. 2 will be described as an example here.

In the drawing, the charging roller 50 is pressed against the photosensitive drum 48, and both are rotatably supported by the cleaning container 66. The path of incidence of the laser light 67 is between the cleaning container 66 and the toner container lid 62a. The developing container 61 and the toner container 62 are adjacent to each other, and the toner in the toner container 62 is fed into the developing container 61 through the openings 62b by the blade members 63 and 64. As described above, there are four types of toner, but the developing device 3
The configurations of 4, 39, 44 and 49 are the same. In this developing method, non-mag toner is used, and the toner is applied onto a developing sleeve 49a driven by a gear pair (not shown) provided between the developing blade 65 and the photosensitive drum 48 to develop the photosensitive drum 48 and the developing drum 49. Jumping development is performed with a slight gap between the sleeves 49a. The cleaning blade 51 a fixed to the cleaning container 66 is the photosensitive drum 48.
The toner remaining on the photosensitive drum 48 is cleaned by being pressed against the toner, and the cleaned toner is stored in the cleaning container 66.

As shown in FIG. 1, the color image forming apparatus (LBP) according to the present embodiment has an outer casing 100,
At the bottom, paper feed cassettes 5 and 6 are provided so as to be detachable from the direction perpendicular to the plane of the drawing. Image forming units 1, 2, 3 and 4 are vertically stacked and arranged above the sheet feeding cassettes 5 and 6 on the right side, and a fixing device 18 is arranged above the image forming unit 1. . A paper discharge tray 20 is provided outside the top of the housing 100. Transfer rollers 14, 15, 16, and 17 are arranged on the photosensitive drums 33, 38, 43, and 48 of each image forming unit.

Transfer material P stored in paper feed cassettes 5 and 6
Paper feed rollers 23 and 24 for pressing and pushing the transfer material P are provided, and the transfer rollers P are fed from the paper feed rollers 23 and 24 through the conveyance guide 7 at timings for transfer, and transfer from the registration rollers 8 and 8 is performed. Transfer material P to the transfer portion of the yellow toner image between roller 14 and photosensitive drum 48.
A transfer belt 9 for transferring the transfer roller 1 and the transfer roller 1
5 and the transfer belt 10 that transfers the transfer material P to the transfer portion of the magenta toner image between the photosensitive drum 43, and similarly, the transfer material from this transfer portion to the transfer portion of the cyan toner image between the next transfer roller 16 and the photosensitive drum 38. A conveyor belt 11 that conveys P, a conveyor belt 12 that conveys the transfer material P from the transfer portion between the transfer roller 16 and the photosensitive drum 38 to a transfer portion of the black toner image between the transfer roller 17 and the photosensitive drum 33, and the transfer roller. A conveyor belt 13 that conveys the transfer material P from the transfer portion between the photosensitive drum 33 and the photosensitive drum 33 to the fixing device 18, and a paper discharge roller 19 that discharges the transfer material P sent from the fixing device 18 through the conveyance guide 25 are provided.

An electric component section 21 containing a DC controller, a DC power source, and a high-voltage power source is provided on the opposite side of the above-described conveying members arranged in the vertical direction with the image forming units 1, 2, 3, 4 interposed therebetween.
A board 22 for converting a signal from the host side into a page description language is arranged above and below the left side of the paper feed cassettes 5, 6.

The above-mentioned members are provided in the housing 100.

In the above, the process cartridge 60
As has already been described in detail, the cartridges are integrally formed as cartridges and are detachably provided on the respective frame bodies 30 of the image forming units 1, 2, 3 and 4. Therefore, since the image forming units 1, 2, 3, 4 can be attached to and detached from the apparatus main body, the process cartridge 60 can be attached to and detached from the frame body 30 together with the image forming units 1, 2, 3, 4 from the apparatus body. is there. Further, the process cartridge 60 can be attached to and detached from the frame 30 while the image forming units 1, 2, 3 and 4 are attached to the apparatus main body.

The process cartridge 60 is not limited to the combination of the photosensitive drum, the charging roller, the developing device and the cleaning device as described above, and the type of each device is also limited. Never,
At least one of the charging means, the developing means, the cleaning means, and the transfer means may be combined with the image carrier, and any process cartridge 60 is attached to or detached from the frame body 30.

Next, the operation of the image forming process will be described in detail according to the order of color image formation.

Signals coming from the host side are yellow (Y), magenta (M), cyan (C), black (B).
One page of signals is stored for each signal of k),
According to the timing of image formation for each color,
It is sent out from the memory part of the substrate 22.

The transfer material P is the paper feed cassettes 5 and 6 to be used.
In accordance with the above, one of the paper feed rollers 23 and 24 rotates, and the transfer material P is advanced to the registration roller 8 through the conveyance guide 7. The photosensitive drum 48 starts rotating according to the timing at which the registration roller 8 advances the transfer material P, and the scanner unit 47 writes with laser light according to the yellow image signal. This electrostatic latent image is developed by the developing device 49 having yellow toner. The developed toner image advances to the position of the transfer roller 14, and this toner image is fed to the paper feed roller 23 or 2
4, the transfer is synchronized with the registration roller 8 and transferred to the transfer material P fed between the photosensitive drum 48 and the transfer portion of the transfer roller 14 by the conveyor belt 9. The transfer roller 14 applies an electric charge having a polarity opposite to that of the toner from the back side of the transfer material, or forms an electric field between the transfer roller 14 and the photosensitive drum 48, so that the toner image formed on the photosensitive drum 48 is transferred onto the transfer material P. It is to be transcribed.

The transfer material P onto which the toner image has been transferred is separated from the photosensitive drum 48 by a curvature because the photosensitive drum 48 is a small-diameter drum, and is adsorbed by the conveyor belt 10 and conveyed. A position detecting means (not shown) for the transfer material P is provided in the middle of the conveyor belt 10, and the image forming unit 3 of magenta starts to operate by the detection signal. The photosensitive drum 43 starts rotating, and the scanner unit 42 writes with laser light according to a magenta image signal. This electrostatic latent image is developed by the developing device 44 having magenta toner. This toner image is transferred by the transfer roller 15 onto the transfer material P sent by the conveyor belt 10.

The transfer roller 15 transfers the toner image formed on the photosensitive drum 43 by applying an electric charge having a polarity opposite to that of the toner from the back side of the transfer material or forming an electric field with the photosensitive drum 43. It is transferred to the material P. At this time, the magenta toner image is transferred so as to overlap the yellow toner image.

Transfer material P on which a magenta toner image has been transferred
Is separated from the photosensitive drum 43 by curvature, and is adsorbed by the conveyor belt 11 and conveyed. At this time, the distance from the position detecting means (not shown) of the transfer material P to the transfer roller 15 needs to be longer than the distance from the exposure position to the transfer roller 15. The timing at which the photosensitive drum 43 starts rotating is estimated from the timing at which the registration roller 8 rotates, and the photosensitive drum 43 starts rotating and charging operation in advance.

At this time, if the distance between the adjacent photosensitive drums, that is, the distance between the image forming units is set smaller than the length of the transfer material P having the minimum size, the transfer material P is at least one photosensitive drum. Since it is sandwiched by the transfer roller, the transfer material P can be more stably conveyed.

In order to stably perform the curvature separation by the photosensitive drum having a small diameter, the photosensitive drum needs to have a diameter of 40 mm or less, preferably 20 to 30 mm.

The next cyan and black image forming processes are similar to those for magenta. However, when the transfer is repeated, the amount of toner of the transfer material P increases toward the later, so the voltage or current amount of the transfer roller is gradually increased.

After the above-mentioned transfer, the photosensitive drums 33, 3 are transferred.
The waste toner remaining on 8, 43, 48 is cleaned by the cleaning means 36, 41, 46, 51.

The transfer material P to which the toner image is transferred is conveyed to the fixing device 18 through the conveying belts 10, 11, 12, 13 and a conveying guide connecting the respective conveying belts to the transfer portion. The fixing device 18 forms a recorded image by melting and fixing the toner image on the transfer material P to the transfer material P by heat and pressure. The transfer material P after the image position fixing is the conveyance guide 25.
After that, the sheet is discharged to the sheet discharge tray 20 by the sheet discharge roller 19.

(Practical Example 1 of Embodiment 1) The image forming units 1, 2, 3 and 4 have the same structure, and mainly the image forming unit 4 will be described (the same applies to the following embodiments and practical examples). As the photosensitive drum 48, an OPC drum having a diameter of 30 mm that can be negatively charged is used. This OPC drum has a structure in which Teflon (trade name) particles are dispersed in the surface layer so as not to be easily scraped and to improve transfer efficiency. The toner used is a non-mag one-component toner having an average particle diameter of 4 to 7 μm, and the leading edge of the developing blade 65 made of urethane rubber is placed on the non-magnetic developing sleeve 49a in the counter direction opposite to the toner moving direction. By abutting, it is applied in a thickness of 30 to 100 μm. A sponge-like roller 49b is in contact with the surface of the developing sleeve 49a and is rotating, and the toner on the developing sleeve 49a is once cleaned. The toner is a toner that is negatively charged, and has a color of yellow (Y), magenta (M), cyan (C), and black (Bk), respectively, and is manufactured by using a crushing method that is a conventional manufacturing method. Was done.

The distance between the photosensitive drum 48 and the developing sleeve 49a is set to 100 to 300 μm, and the toner on the developing sleeve 49 becomes a latent image on the photosensitive drum 48 due to the bias voltage applied to the developing sleeve 49a. Fly towards.

The charging roller 50 has a sponge inside, and the charging noise can be reduced even when an alternating bias voltage is applied.

In the image forming unit 4, the frame body 30 is made of sheet metal, and the scanner unit 47 and the process cartridge 60 are integrally mounted on the frame body. The scanner unit 47 is entirely made of a plastic mold to facilitate positioning and to prevent dust from entering.

(Practical Example 2 of Embodiment 1) As the image forming unit 4, the photosensitive drum 48 has a diameter 3 which allows negative charging.
A 0 mm OPC drum was used. This OPC drum has a structure in which Teflon (trade name) particles are dispersed in the surface layer so as not to be easily scraped and to improve transfer efficiency. As the toner, a non-mag one-component toner having an average particle diameter of 4 to 7 μm is used. Is applied to the developing sleeve 49a, which is an elastic body and is semi-conductive, to have a thickness of 30 to 100 μm. A sponge-like roller 49b is in contact with the surface of the developing sleeve 49a and is rotating, and the toner on the developing sleeve 49a is once cleaned. The toner is a toner that is negatively charged and has a color of yellow (Y), magenta (M), cyan (C), and black (Bk), and was manufactured by using a polymerization method. Developing sleeve 49a
Is in contact with the photosensitive drum 48, and is 0.2 to 1.0 mm.
The developing sleeve 49a is set so as to be dented, and the developing sleeve 49a is biased by the bias voltage applied to the developing sleeve 49a.
The toner on a adheres to the latent image on the photosensitive drum 48.

The charging roller 50 has a sponge inside and can reduce the charging noise even when an AC bias voltage is applied.

In the image forming unit 4, the frame 30 is made of sheet metal, and the scanner unit 47 and the process cartridge 60 are integrally mounted on the frame 30. The scanner unit 47 is wholly made of a plastic mold to facilitate positioning and to prevent dust from entering.

As described above, the laser exposure device and the process cartridge are integrally formed to form an image forming unit, and four image forming units are vertically arranged to form a color image. The device can be configured in a small size, at high speed, with easy maintenance, and at low cost.

In particular, since the scanner unit can be arranged horizontally, the polygon mirror can be stably rotated at high speed around the vertical axis. Further, since the light from the polygon mirror can be directly incident on the photosensitive drum without being bent, the structure is simplified and is less susceptible to the vibration of the main body.

Furthermore, since four image forming units are vertically stacked, the process cartridge, which is a replacement part, is arranged near the end of the apparatus main body, and the process cartridge can be easily replaced. There is.

In the above-described embodiments, the process cartridge has been described as having the image carrier, the charging means, the developing means, and the cleaning means. However, when spherical toner is used as the toner, the transfer rate is close to 100%. Therefore, it is possible to adopt a configuration that requires no cleaning means. In this case, the process cartridge is an integrated cartridge having an image carrier, a charging unit, and a developing unit.

As another embodiment, the process cartridge can be configured to have an image carrier, a charging means, a developing means, a cleaning means, and a transfer means. In this example, since the transfer means is attached to the process cartridge, the process cartridge can be replaced more easily.

In the above construction, the number of image forming units arranged vertically is four, but this number is not limited, but at least three are required for color image formation. Further, when forming an image of two colors of cyan and black, for example, two may be used.

(Embodiment 2) FIG. 4 shows another embodiment 2 according to the present invention.

The second embodiment has the same structure using the image forming unit, but once the toner images are sequentially transferred to the intermediate transfer belt, and when the four color toners are superposed, they are collectively transferred to the transfer material. To do.

Another embodiment 2 using the present invention according to FIG.
Will be explained. Image forming units 101, 102, 10
Since 3 and 104 are the same as those used in FIG. 1, they are represented only by the display of figures without reference numerals, and detailed description thereof is omitted here.

However, in the image forming unit of FIG. 1, the photosensitive drum is rotated to the left, but in the embodiment of FIG. 4, since it is rotated to the right, the charging roller 122 is arranged on the lower side and the developing device 123 is arranged on the upper side. It is located in. Also, the cleaning member 1
24 is arranged on the lower side.

Image forming units 101, 102, 10
The photosensitive drums in 3, 104 rotate in the directions of the arrows, and the image forming units 101, 102, 103, 10
The toner image formed in No. 4 is sequentially transferred to the intermediate transfer belt 110. At this time, since the intermediate transfer belt 110 is used, the transfer is performed from the photosensitive drum to the intermediate transfer belt 11
It is performed twice from the intermediate transfer belt 110 to the transfer material P to 0. Therefore, the image forming unit 10
It is appropriate to reverse the order in which the colors 1, 102, 103, 104 are overlapped with the order described in FIG.

When the four color toners are transferred, the transfer material P in the paper feed cassette 105 is a separation pad for pressing the corner of the paper feed roller 107 and the transfer material P provided facing the paper feed roller 107. By (not shown), the sheets are separated and fed one by one. The transferred transfer material P is fed by the transport guide 13
1 is conveyed to the transfer portion between the drive roller 116 and the transfer roller 117. At this time, the intermediate transfer belt 110
The position of the intermediate transfer belt 110 is detected by the detection element 121 that detects the mark written on the intermediate transfer belt 110 by the reflected light so as to be synchronized with the leading edge of the image formed above, and in response to this signal. The transfer material P is conveyed to the transfer section. In this way, the toner images formed on the intermediate transfer belt 110 are collectively transferred onto the transfer material P by the transfer roller 117.

Both ends of the intermediate transfer belt 110 are stretched by a driven roller 115 and a driving roller 116 so that there is no slack. Where the intermediate transfer belt 110 and the photosensitive drums of the image forming units 101, 102, 103, 104 are in contact with each other for transfer, the rollers 111, 112, 113, 114 are arranged so that the rollers 111, 112, 113, 114 are in good contact with the photosensitive drums. 110 is supported from the back side.

The transfer material P on which the toner image is transferred is conveyed to the fixing device 119 by the conveying guide 118. The fixing device 119 forms a recorded image by melting and fixing the toner image on the transfer material P to the transfer material P with heat and pressure. The transfer material P on which the image has been fixed is discharged to the discharge tray 120 by the discharge rollers 132 via the conveyance path.

In the figure, an electrical component section 108 containing a DC controller, a DC power source, and a high-voltage power source, and a substrate 109 for converting a signal coming from the host side into a page description language are the back portions of the image forming units 101, 102, 103, 104. It is arranged vertically.

(Embodiment 3) Another embodiment 3 of the present invention will be described with reference to FIG. In this embodiment, the transfer portion of the second embodiment is replaced with the above. Since the image forming units 101, 102, 103 and 104 are the same as those used in FIG. 1, detailed description thereof will be omitted here.

Image forming units 101, 102, 10
The photosensitive drums in 3, 104 rotate in the direction of the arrow, and the image forming units 101, 102, 103, 104
The toner image formed in 1 is sequentially transferred to the intermediate transfer belt 110. When the four color toners are transferred, the transfer material P in the paper feed cassette 105 is fed one by one by the paper feed roller 107 and a separation pad (not shown) provided so as to face the paper feed roller 107. Separated and sent. At this time, since the intermediate transfer belt 110 is used, the transfer is
Will be held once.

The transferred transfer material P is transferred to the transfer guide 131.
Is conveyed to the transfer section. At this time, in synchronization with the leading edge of the image formed on the intermediate transfer belt 110,
The transfer material P is conveyed to the transfer section. Intermediate transfer belt 110
The toner images formed on the transfer roller 117 are collectively transferred to the transfer material P by the transfer roller 117. At this time, the toner image is transferred to the lower surface of the transfer material P.

Both ends of the intermediate transfer belt 110 are stretched by a driven roller 115 and a driving roller 116 so that there is no slack. Where the intermediate transfer belt 110 and the photosensitive drums of the image forming units 101, 102, 103, 104 are in contact with each other for transfer, the rollers 111, 112, 113, 114 are arranged so that the rollers 111, 112, 113, 114 are in good contact with the photosensitive drums. 110 is supported from the back side.

The transfer material P having the toner image transferred to the lower side is
It is conveyed to the fixing device 119 by the conveyance guide 118. The fixing device 119 forms a recorded image by melting and fixing the toner image on the transfer material P to the transfer material P with heat and pressure. The transfer material P on which the image has been fixed is discharged to the discharge tray 120 by the discharge rollers 132 via the conveyance path.

As described above, with the configuration of the second or third embodiment, it is not necessary to vertically convey the transfer material such as paper, and the intermediate transfer belt is used to convey the transfer material. The distance could be greatly shortened. Further, by using the intermediate transfer belt, registration of the leading edge of the image is relatively easy, and the minimum number of elements for detecting the leading edge of the transfer material as described in FIG. 1 is required. The configuration can be simplified.

In each of the embodiments, the process cartridge 60 is detachably mounted on the frame 30. This detachability means that the user or service person can freely perform the maintenance. However, the process cartridge 60
May be coupled to the frame 30 with a fastening member using a tool so that they can be assembled and disassembled. In this case, the image forming unit can be attached to and detached from the apparatus main body.

[0081]

According to the first aspect of the present invention, a plurality of image forming units are vertically arranged, and a sheet feeding unit and a fixing unit are provided on both upper and lower sides of the image forming units so that the transfer material is vertically aligned along the image forming unit. Since the conveyance path is provided, it is possible to provide a small-sized, high-speed, inexpensive, easy-to-handle, easy-to-maintain color image forming apparatus.

In the second aspect of the present invention, a plurality of image forming units are vertically arranged, an intermediate transfer member is arranged vertically along each of the image forming units, and the intermediate transfer member is provided downstream in the moving direction. Since the paper unit, the transfer unit, and the fixing unit are provided, it is possible to provide a small-sized, high-speed, inexpensive, and easy-to-handle image forming apparatus. In particular, the transfer material is easily transported and has high reliability.

According to a third aspect of the present invention, in the first aspect, the image forming unit has a frame body that can be attached to and detached from the apparatus main body of the color image forming apparatus, and the frame body is provided with the image exposure means and the process cartridge. Therefore, the image forming unit can be easily attached to and detached from the main body of the color image forming apparatus, and maintenance can be facilitated.

According to a fourth aspect of the present invention, in the second aspect, the image forming unit has a frame body that is attachable to and detachable from the apparatus main body of the color image forming apparatus, and the frame body is provided with the image exposure means and the process cartridge. Therefore, the image forming unit can be easily attached to and detached from the main body of the color image forming apparatus, and maintenance can be facilitated.

According to the fifth aspect of the present invention, in the first or third aspect, the distance between the image bearing members is smaller than the length of the transfer material having the minimum size, so that the transfer material can be conveyed smoothly and stably.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the image carrier has an outer diameter of 40 m.
Since the drum is a small-diameter drum having a diameter of m or less, the curvature separating action is strong on the transfer material, and the transfer material is reliably separated from the image carrier after the transfer.

In a seventh aspect of the present invention, in any one of the first to sixth aspects of the invention, since the image exposing means is a laser exposing means, the exposure width is small and the image carrier is small. And thus has the advantage of reducing the size of the color image forming apparatus.

According to an eighth aspect of the present invention, in the first or second aspect of the invention, the process cartridge can be attached to and detached from the frame of the image forming unit, so that the color image forming apparatus can be manufactured, handled and maintained easily. effective.

The ninth aspect of the present invention has the effect of facilitating the manufacture, handling, and maintenance of the color image forming apparatus in the first or second aspect, because the image forming unit is detachable from the apparatus main body. .

In the tenth aspect of the present invention, the process cartridge can be attached to and detached from the image forming unit in the state where the image forming unit is attached to the image forming unit in the eighth or ninth aspect of the invention, so that assembling, handling and maintenance are simplified. Contribute to.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a schematic configuration of a laser beam printer according to a first embodiment of the present invention.

FIG. 2 is a perspective view of an image forming unit used in the laser beam printer of FIG.

FIG. 3 is a vertical sectional view of a process cartridge of the image forming unit shown in FIG.

FIG. 4 is a vertical cross-sectional view showing another embodiment 2 of the laser beam printer using the present invention.

FIG. 5 is a vertical sectional view showing another embodiment 3 of the laser beam printer using the present invention.

[Explanation of symbols]

 1, 2, 3, 4 Image forming unit 33, 38, 43, 48 Photosensitive drum 14, 15, 16, 17 Transfer roller 110 Intermediate transfer belt

Claims (10)

[Claims] 1. An image forming device comprising an image exposing means, an image carrier, a charging means, a developing means each having a different color toner, or a cleaning means in addition to these, or a cleaning means and a transfer means in addition to these. A plurality of units are arranged vertically, and a transport path and a transport means for transporting the transfer material in the vertical direction through the plurality of image forming units, a paper feeding means for feeding the transfer material to the transport path, and a transfer material after transfer is fixed. A color image forming apparatus provided with a fixing unit, the image forming unit, a process cartridge in which at least one of a charging unit, a developing unit, a cleaning unit, and a transfer unit and an image carrier are integrated, and an image exposing unit. A color image forming apparatus comprising: 2. A plurality of image forming units each having an image exposing unit, an image bearing member, a charging unit, a developing unit having a toner of a different color, or an image forming unit having a cleaning unit in addition to these units are removably mounted on the apparatus main body. Are arranged side by side, and an intermediate transfer member that moves in the up-and-down direction is arranged between each image carrier and the transfer unit of the plurality of image forming units, and the transfer material is fed to the downstream side in the moving direction of the intermediate transfer member. A color image forming apparatus provided with a paper feeding means, a transfer means, and a fixing means for fixing the transfer material after the transfer, wherein the image forming unit includes at least one of a charging means, a developing means, and a cleaning means, and an image bearing unit. A color image forming apparatus comprising an image forming unit including a process cartridge having an integrated body and an image exposing unit. 3. The color according to claim 1, wherein each of the image forming units has an image exposing unit and a process cartridge in a frame body, and each frame body is detachable from the apparatus main body. Image forming apparatus. 4. The color according to claim 2, wherein each of the image forming units has an image exposure unit and a process cartridge in a frame body, and each frame body is detachable from the apparatus main body. Image forming apparatus. 5. The color image forming apparatus according to claim 1, wherein the distance between the image carrier and the image carrier is smaller than the length of the minimum size transfer material. 6. The color image forming apparatus according to claim 1, wherein the image carrier constituting the image forming unit is a small-diameter drum having an outer diameter of 40 mm or less. 7. The color image forming apparatus according to claim 1, wherein the image exposing unit is a laser exposing unit. 8. The color image forming apparatus according to claim 1, wherein the process cartridge is integrally formed as a cartridge and is attachable to and detachable from the frame of the image forming unit. 9. The color image forming apparatus according to claim 1, wherein the image forming unit is removable from the apparatus main body. 10. The color image forming apparatus according to claim 8, wherein the process cartridge is attachable to and detachable from the image forming unit attached to the apparatus main body.